Glossary - Aquaculture operations in floating HDPE cages

Anoxia deficiency or absence of oxygen in the blood and tissues. Ballast chain the large chain connecting the mooring point on the sea floor (anchor or concrete block) to the mooring line connected to the grid system.

This chain has the function of cushioning (absorb) the drag forces on mooring points generated by waves and currents on the cages.
Barotrauma injury due to pressure variation exposure, such as decompression illness, ears and sinus squeezes, embolism, etc.
Batch or lot, i.e. a group of specimens homogenous for at least one characteristic (usually age) and cultured together in the same rearing unit (net pen).
Beaufort scale scale referring to the strength of the wind and the relevant sea status. It is empirical and based on the observed sea status. It ranges from 0 (calm) to 12 (hurricane).
Biomass the total live weight of a group (or stock) of living organisms (e.g. fish, plankton) or of some defined fraction of it (e.g. fish spawners), in an area, at a particular time.
Bridles the mooring ropes that connect the cage collar to the grid system. Bridles are usually connected to the corner plates and tied on the collars, either onto the high-density polyethylene (HDPE) pipes or on specific supports built in the collar.
Bracket a plastic or metallic component of the cage collar. Each cage is equipped with a number of these, equidistant along the collar circumference. These have the function of keeping assembled the HDPE rings of the collar and to provide the collar with stanchions holding a handrail, for facilitating surface operations.

Cohort a subpopulation; if a population is divided into several groups based on spawning date, the population is divided into age cohorts.
Collar the floating cage structure made with HDPE pipes on which the cage net is hung.
Denier unit of measure of linear mass density of textiles; it is referred to the mass in grams of 9 000 m of a single filament fibre.
Fetch the distance the wind can blow over the sea; usually expressed in kilometres or nautical miles. Fetch distance and wind force determine the size of the waves at a given site.
Fingerlings related to any fish from advanced fry to the age of one year from the date of hatching regardless of size.
Fluke the part of the anchor that becomes embedded in the sea bottom, providing resistance to dragging forces.
Footprint (farm) the total area occupied by a farm, including the submerged components of the mooring system and the mooring lines.
Fouling the accumulation of aquatic organisms that attach to and grow on underwater objects, such as ship hulls, harbour structures, net cages and rafts.
Galvanized metal component (usually iron or steel) protected through a coating of zinc.
Jump net the exposed or visible part of a net cage from the waterline rope to the top rope; it is usually fixed on the upper part of the stanchion or the handrail of the floating collar.
Mesh one of the open spaces between the cords of a net. The size of netting mesh is measured as the length of one mesh side, e.g. a 25 mm mesh (also known as “bar size”). The mesh size measurement can also be indicated as “stretched size”, which is the size of netting mesh measured as the length of a stretched mesh.
Net cage the structure holding the fish stock; it is made of netting material and ropes seamed together. It may have loops or rings to fix it to the floating (collar) or sinking (sink tube) components of the fish cage.
Netting for the purposes of this manual, “netting” refers to an open mesh fabric (whether in bulk or incorporated into a net cage), whereas “net” refers to a ready-to-use product made from netting (e.g. cage net or fishing net).
No fishing zone an area of the marine environment together with its overlying water and associated flora and fauna where no fishing is allowed and which is protected legally by law or regulations.
Pellet agglomerated feed formed by compacting and forcing it through die openings by a mechanical extrusion process.
Purse seine nets characterized by the use of a purse line at the bottom of the net. The purse line enables the net to be closed like a purse and thus retain all the fish caught.
Shackle a movable metal link, U-shaped, used to connect mooring components, chains, thimbles, etc. It is fixed trough a bolt, which is usually secured with a cotter pin.
Shank the central, straight part of an anchor to which the fluke is connected on one end and the stock on the other end.
Sinker system the weights and other structures connected to the net cage to sink the net and maintain its volume and shape.
Siting the process of site selection, up to the detail of exact mooring location and orientation.
Spliced eye a splice formed by bending a rope end back and splicing it into the rope so that a loop is formed.
Splicing a semi-permanent joint between two ropes or two parts of the same rope by partly untwisting and then interweaving their strands.
Stanchion the vertical part of a bracket holding the handrail pipe in a floating cage unit.
Tenacity unit of measure of fibre strength. It is calculated dividing the tensile strength of a fibre by the denier.
Tensile strength the strength of a fibre or yarn measured as the maximum tension the material can withstand without breaking.
Thimble a loop of metal or plastic having a groove at its outer edge for a rope or cable. Used for protecting ropes from abrasion. It is usually mounted inside a spliced eye.
Tripping line rope installed on the anchor, opposite the fluke, useful to launch the anchor during installation or to remove the anchor from its embedding.
Wave crest the highest part of a wave. A wave length is measured from crest to crest.
Zipping line a rope connected to the anchor crowne used to recover an embedded anchor.